1553962721 has 2 divisors, whose sum is σ = 1553962722. Its totient is φ = 1553962720.

The previous prime is 1553962693. The next prime is 1553962723. The reversal of 1553962721 is 1272693551.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1168272400 + 385690321 = 34180^2 + 19639^2 .

It is a cyclic number.

It is not a de Polignac number, because 1553962721 - 2¹⁰ = 1553961697 is a prime.

Together with 1553962723, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (1553962723) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 776981360 + 776981361.

It is an arithmetic number, because the mean of its divisors is an integer number (776981361).

Almost surely, 2^1553962721 is an apocalyptic number.

It is an amenable number.

1553962721 is a deficient number, since it is larger than the sum of its proper divisors (1).

1553962721 is an equidigital number, since it uses as much as digits as its factorization.

1553962721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 113400, while the sum is 41.

The square root of 1553962721 is about 39420.3338519602. Note that the first 3 decimals coincide. The cubic root of 1553962721 is about 1158.2799321355.

The spelling of 1553962721 in words is "one billion, five hundred fifty-three million, nine hundred sixty-two thousand, seven hundred twenty-one".